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logical device
logical subsystem (LSS)
logical unit
logical unit number (LUN)
logical volume
SCSI
SCSI host systems
SCSI ID
service personnel
A pointer to a logical volume on a storage server.
The pointer enables a host system to access the
logical volume. For the ESS, the logical device
represents a logical volume.
The LSS is a logical "container" for RAID-5 arrays,
disk groups, and the volumes that are located on
those arrays or disk groups. One SSA Adapter
accesses an LSS primarily. One or more logical
subsystems can exist on the ESS. In general, the
ESS associates a given set of devices with only
one logical subsystem.
For System/390 hosts, a logical subsystem
represents a controller.
The Small Computer System Interface (SCSI) term
for a logical disk drive.
LUN is a SCSI term for the field in an identifying
message that is used to select a logical unit on a
given target.
The storage medium associated with a logical disk
drive. A logical volume typically resides on one or
more storage devices. For the ESS, you define this
unit of storage; the logical volume resides on a
RAID-5 array, and is spread over 6 + P or 7 + P
drives, where P is parity. A logical volume can also
reside on a non-RAID array on one storage device.
For CKD, you can define the logical volume size by
the device emulation mode (3390 or 3380 track
®
format). For UNIX
, Microsoft
Microsoft Windows 2000
fixed-block format, the size is 0.5 GB to 224 GB.
®
For AS/400
operating systems in the fixed-block
format, the size is 4.19, 8.59, 17.55, or 36 GB.
®
Note: The AIX
operating system views a logical
volume as a logical disk or a hard disk
(hdisk).
See small computer system interface .
Identifies host systems that you attach to the ESS
with a SCSI interface. Such host systems run on
UNIX, OS/400, Windows NT, Windows 2000, or
Novell NetWare operating systems.
A unique identifier (ID) assigned to a SCSI device
that is used in protocols on the SCSI interface to
identify or select the device. The number of data
bits on the SCSI bus determines the number of
available SCSI IDs. A wide interface has 16 bits,
with 16 possible IDs. A SCSI device is either an
initiator or a target.
Individuals or a company that you have authorized
to service your ESS. This term also refers to a
®
®
Windows NT
, and
®
operating systems in the
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